1. Field of the Invention
The invention relates to a keyswitch device, more particularly to a keyswitch device that has a stable and relatively flat structure which comprises relatively few components.
2. Description of the Related Art
As shown in FIGS. 1 and 2, an electronic device 9, such as a personal digital assistant, a notebook computer or a keyboard, includes a conventional keyswitch device 90 serving as a command input device. The conventional keyswitch device 90 includes a supporting seat 91, a key cap 92 for pressing, a first balancing member 93 and a second balancing member 94 connected pivotally between the supporting seat 91 and the key cap 92, a circuit board 95, and a resilient dome 96 disposed on the circuit board 95 and having a top surface that is in contact with a bottom surface of the key cap 92.
The supporting seat 91 includes a limiting sleeve 911 and two limiting walls 912, and the key cap 92 includes a shaft 921 extending movably into the limiting sleeve 911 and a block 922 disposed movably between the limiting walls 912. This configuration is for inhibiting horizontal movement and allowing only vertical movement of the key cap 92 relative to the supporting seat 91. The supporting seat 91 further includes a plurality of vertically-extending first hook members 913. Each of the first hook members 913 has a hook end. The keycap 92 further includes a plurality of second hook members 923 for engaging respectively the first hook members so as to prevent separation of the keycap 92 from the supporting seat 91 during the vertical movement of the keycap 92.
When the user presses the key cap 92, the resilient dome 96 is indirectly pressed and subsequently presses the circuit board 95 to generate a corresponding signal. The first and second balancing members 93 and 94 serve to reduce inclination of the key cap 92 when the key cap 92 moves vertically.
As such, the supporting seat 91 and the key cap 92 of the conventional keyswitch device 90 can only be made of plastic or metal by injection molding. Nonetheless, the plastic components must be made with at least a predetermined thickness during the injection molding process in order to maintain a required strength, thereby undesirably increasing the manufacturing cost and the overall height of the keyswitch device 90. A conventional way for increasing the strength of the plastic supporting seat 91 is to laminate an iron sheet on a bottom side of the supporting seat 91, which would further undesirably incur material and labor costs. Metal supporting seat 91 and the keycap 92 by injection molding also have the drawback of relatively high manufacturing cost.